I have an obvious bias towards monolith, Mistwalker doesnt have as large of libraries as the other 2, nor have they been around as long. And Level 5 I have only played Jeanne D'arc DQ8 and Rogue Galaxy, their games are excellent though. But when it comes down to who actually makes the "best" JRPGs? Thats a tough call, I would probably go with miswalker as having the most complete package, keep in mind i have only played The Last Story though, so I may not be the best person to ask. I say that because good characters, good extremely unique combat, driving the genre forward etc. Monolith is much more story heavy (But its takahashi running the show, thats to be expected :P), Xenosaga, Baten Kaitos was the beginning and I think Xenoblade kind of merged some aspects from both those series into one (the gorgeous visuals from BK mixed with story and character aspects from Xenosaga, but at the same time making it its on unique experience). Level-5 just makes beautiful games, with interesting combat, the stories have been a bit more on the light side, but they are up there with the JRPG elite thats for sure.